NMR spectra of dilute spins under slow sample‐spinning and homonuclear decoupling

Magnitudes and Orientations of 31P Chemical Shielding Tensors in Pt(II)−Phosphine Complexes and Other Four-Fold Coordinated Phosphorus Sites

31P MAS and double-quantum filtered 31P MAS NMR experiments at and near the n = 0 rotational resonance condition, as well as off-magic angle spinning 31P NMR experiments on two polycrystalline samples of Pt(II)-phosphine thiolate complexes are reported. Numerical simulations yield complete descriptions of the two 31P spin pairs. 195Pt MAS NMR spectra are straightforward to obtain but sensitively reflect only some parameters of the 195Pt(31P)2 three-spin system. Based on the 31P NMR results obtained and in conjunction with a large body of literature data and irrespective of the chemical nature of the specimen, a unified picture of the dominating motif of 31P chemical shielding tensor orientations of phosphorus sites with 4-fold coordination is identified as a local (pseudo)plane rather than the directions of P element bond directions.

Spectral editing in solid-state NMR using scalar multiple quantum filters

In this paper we describe the use of heteronuclear scalar couplings in solid-state NMR in order to generate multiple-quantum filtering (MQF) pulse sequences. These sequences can be used to edit CP/MAS spectra according to carbon multiplicity. Analytic expressions for the intensity of the MQF signals are obtained using the standard product operator formalism. Experiments that demonstrate the technique are shown in powder samples of camphor and a tripeptide.

Influence of proton chemical-shift anisotropy on magic-angle spinning spectra of hydrate crystals

It is shown that the proton chemical-shift anisotropy of hydrate crystals affect dipolar powder pattern at 7.0 T. This may be clearly observed via an asymmetric envelope of dipolar spinning sidebands in magic-angle spinning proton spectra.

Solid Me3Sn(O2CH): molecular and spin dynamics as viewed by 1H, 13C and 119Sn nuclear magnetic resonance spectroscopy

Because of favourable dynamic properties in the solid state, crystalline trimethyltin formate, Me3Sn(O2CH), 1, offers quite unique possibilities to probe questions related to molecular dynamics (2 pi/3 Me3Sn reorientation) and to structural aspects (rigidity of the polymeric backbone, effectively isolated 1H-13C spin pair in the bidentate chain-building formate anion) by 1H, 13C and 119Sn high-resolution solid-state nuclear magnetic resonance (NMR) methods. The combined use of various one- (1D) and two-dimensional (2D) variable-temperature NMR experiments, including consideration of the short-time-cross-polarization (CP) behaviour of the 1H-13C spin pair in 13C-labelled Me3Sn(O2*CH), 1*, yields a fairly comprehensive description of the solid-state structure of 1, also in the absence of the single-crystal X-ray structure determination of 1. Taking advantage of the anisotropic polarization transfer within the formate 1H-13C spin pair allows to relate the orientation of the 1H-13C dipolar interaction, i.e. the C-H bond direction to the principal axes system of the 13C shielding tensor of the formate 13C from static 13C powder patterns of 1*.